Washington — The Supreme Court on Monday agreed to review a lower court decision that invalidated a rule from the Biden administration that aimed to address the proliferation of crimes involving “ghost guns.”

The regulation at issue was implemented by the Bureau of Alcohol, Tobacco, Firearms and Explosives in April 2022 and imposed a series of requirements on manufacturers and sellers of so-called ghost guns, which are unserialized firearms that can be assembled from kits sold online.

ATF’s rule changed the definition of “firearm” under the Gun Control Act to include certain weapon parts kits, and clarified that it includes partially completed parts such as the frame or receiver. As a result of the regulation, covered manufacturers and sellers have to obtain licenses, mark their products with serial numbers, run background checks and keep purchase records, which are all required for firearms made and sold in the U.S.

The rule applies to all ghost guns, including those made with 3D printers or sold as assembly kits. 

A group of gun owners, advocacy groups and ghost gun distributors filed a lawsuit against ATF in August 2022, arguing that the two portions of its rule, regarding the term “frame or receiver” and definition of “firearm,” exceeded its authority. A federal district court in Texas sided with the challengers, finding that the Gun Control Act doesn’t “cover weapon parts, or aggregations of weapon parts,” regardless of whether they can be assembled into “something that may fire a projectile.”

The district court invalidated the entire regulation, including those that were not at issue in the lawsuit.

The Biden administration appealed, and the U.S. Court of Appeals for the 5th Circuit halted the lower court’s order as to the unchallenged portions of the rule. The Supreme Court then paused the full decision in a 5-4 ruling, allowing ATF to enforce the restrictions while legal proceedings continued. Chief Justice John Roberts and Justice Amy Coney Barrett joined with the three liberal justices in the majority.

The 5th Circuit later ruled that the Gun Control Act’s definition of “firearm” doesn’t encompass weapon parts kits, and invalidated the provision of the rule involving the term “frame or receiver.”

The Justice Department asked the Supreme Court to review the appeals court’s decision in February, arguing that it contradicts the plain text of the Gun Control Act.

“Under the Fifth Circuit’s interpretation, anyone could buy a kit online and assemble a fully functional gun in minutes — no background check, records, or serial number required,” it told the Supreme Court. “The result would be a flood of untraceable ghost guns into our nation’s communities, endangering the public and thwarting law-enforcement efforts to solve violent crimes.”

The Biden administration told the court that weapon parts kits can be converted into a fully functional firearm in just 21 minutes, and ghost guns allow felons, minors and others barred from buying firearms to circumvent the law.

If left in place, the 5th Circuit’s ruling would give the manufacturers and distributors of weapons parts the “green light to resume unfettered distribution” without background checks, records, or serial numbers, posing an “acute threat” to public safety, the Biden administration said.

It noted that since 2017, there has been a 1,000% increase in the number of ghost guns recovered by law enforcement each year.

The challengers to ATF’s rule also urged the Supreme Court to decide its validity “once and for all.” They told the high court in a filing that the provisions of the rule are “fundamentally incompatible” with the Gun Control Act’s definition of firearm.

“This expanded definition upsets the delicate balance struck by Congress between the commercial production and sale of firearms and the non-commercial making of firearms by law-abiding citizens,” the group said.

They accused the Biden administration of seeking to destroy the industry that caters to law-abiding citizens making their own guns and said that if the definition of “firearm” is now considered unsatisfactory, it’s an issue for Congress to address.

“ATF is not free to expand the scope of the GCA without Congress’s blessing,” the challengers argued.

The case will be argued in the Supreme Court’s next term, which begins in October.